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Unregulated Engine Emissions and TheirUnregulated Engine Emissions and Their
Control Usin DOC, PFF and CRTControl Usin DOC, PFF and CRT
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IntroductionIntroduction
The increasing use of diesel engines due to their fuel economy,durability and power advantages has contributed to the sum total ofexhaust emissions.
Need of clearly understanding these emissions. Emission can be classified into two broad categories-
egu ate em ss ons
Unregulated emissions
Most of the emission regulations in the world are mainly concernedabout regulated emissions.
Need to reduce the unregulated emissions.
Unre ulated emissions are more challen in to com are amoninvestigators for several reasons.
Vast number of unique compounds that exist in combustionexhaust roducts.
Requires expensive analysis techniques [Mullen et al1].
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Major Unregulated Emission CompoundsMajor Unregulated Emission Compounds
Major unregulated emissions:
PAHs
Carbonyl compounds BTEX etc.
s nown or t e r carc nogen c propert es.
No strict regulations for PAHs emission. PAHs toxicity is very
structurally dependent.
A carbonyl group is a functional group composed of a carbon atomdouble-bonded to an oxygen atom.
, ,ethylbenzene, and xylenes.
Have harmful effects on the central nervous system.
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Major Unregulated Emission CompoundsMajor Unregulated Emission Compounds
Fig 2 Carbonyl Group, Aldehyde and
Fig 1 Priority listed PAHs. *Not included in priority list,,
human carcinogen). [Ravindra et al7]
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Measurement Techniques for Unregulated Emission from CIMeasurement Techniques for Unregulated Emission from CI
EnginesEngines Karavalakis et al, have performed experiments for determining the regulated and
unregulated emissions
.
For determining the carbonyl compounds, they have collected the samples in a 3LTedlar bags.
.
Cartridges contains 2, 4-dinitrophenylhydazine on silica substrate.
By using ultra-violet visible detector, carbonyl-DNPH derivatives were analyzed.
co umn was use or t e separat on o car ony compoun s.
For determining the PAH and nitro-PAH, samples were collected on glass fiber
filter.
na y a gas c romatograp g ent w t a mass spectrometr c
detector (Agilent 5975B) was used for the PAH and nitro-PAH analysis.
Tan et al, have used five different diesel fuel with different sulfur content
or t e measurement, t ey ave use an mu t -component gas ana yzer.
capable of measuring over 25 gaseous components including the measurement ofunregulated emissions (HCHO, MECHO and SO2) also. Paper #
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Measurement Techniques for Unregulated EmissionMeasurement Techniques for Unregulated Emission
Karavalakis et al8, have performed experiments for determining theregulated and unregulated emissions by a passenger vehicle usingdiesel/biodiesel blends under ADC (Athens driving cycle) andNEDC (New european driving cycle). ute w t a r n ut on tunne . For determining the carbonyl compounds, C18 column was used.
For determining the PAH and nitro-PAH- glass fiber filter, Gas
were used.
For the measurement, AVL PEUS multi-component gas analyzer
. Capable of measuring over 25 gaseous components including the
measurement of unregulated emissions (HCHO, MECHO and
2 .
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Measurement Techniques for Unregulated EmissionMeasurement Techniques for Unregulated Emission
Cheung et al10 have performed experiments on a four cylinder direct
injection diesel engine for regulated and unregulated emission withULSD and its blends with ethanol as fuels.
, ,formaldehyde, ethanol etc) by using the Air-sense multi-
component gas analyzer. t ano was ca rate y an n rect way.
Kept the engine running for some time till the exhaust gas
temperature, cooling water temperature, lubricating oil
temperature and CO2 gas concentration in the exhaust stabilizes.
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Effect of Engine Operating Condition and FuelEffect of Engine Operating Condition and Fuel
Com osition on Unre ulated EmissionCom osition on Unre ulated Emission
Effect of diesel/biodiesel blends under ADC and NEDC. [Karavalakis8
Main focus was to investigate the impact of regulated andunregulated emissions with the use of diesel/biodiesel blends
.
Carbonyl compounds (CBCs), Polyaromatic hydrocarbons
(PAHs) and Nitro-PAHs have been measured. our erent ue s, ese an t ree en s w t , ,
biodiesel from soybean oil were used for the experiment.
Formaldehyde was the major compound in both the cases which
was o owe y aceta e y e. Determined 11 PAHs and 5 nitro-PAHs.
Major PAHs emission were of low molecular weight which arefollowed by higher molecular weight PAHs.
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Effect of Engine Operating Condition and FuelEffect of Engine Operating Condition and Fuel
Com osition on Unre ulated EmissionCom osition on Unre ulated Emission
Table 1: Emissions of carbonyls (mg km-1) from diesel fuel and biodiesel blends when thevehicle operated over NEDC and ADC. [Karavalakis et al8]
Carbonyls(mg km-1) NEDC ADC
Diesel B5 B10 B20 Diesel B5 B10 B20Formaldehyde 6.84 5.46 4.61 3.64 11.1 7.74 6.55 4.35
Acetaldehyde 2.86 2.24 1.9 0.49 3.82 4.05 2.1 1.58
Acrolein/acetone 0.73 0.75 2.31 2.2
Propionaldehyde 2 1.56 0.96 1.02 2.89 0.67 0.71
Crotonaldehyde 1.72 1.75 1.89 1.42 3.49 3.37 3.99
Methacrolein 3.51 14.3 2.24 3.3
2-Butanone 0.82 0.85 1.38 2.04
Butyraldehyde 3.81 4.3 2.46 1.52 7.75 7.87 6.23 5.47
Benzaldehyde 3.58 3.76 4.17 3.62 3.98 6.75
Valeraldehyde 5.94 5.47 2.56 12.8 9 11.1 1.29
p-Tolualdehyde 1.34 1.87 3.15 2.28 2.82 6.88 Hexanaldehyde 0.63 0.47 0.56 7.86 5.66 6.35
.
Lower saturated aromatic hydrocarbons in biodiesel blendsresponsible for lower HCHO emission for higher blends.
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Effect of Engine Operating Condition and FuelEffect of Engine Operating Condition and Fuel
Composition on Unregulated EmissionComposition on Unregulated Emission
Effect of different sulfur content. [Tan et al9]
Performed ex eriment on a li ht dut diesel en ine with different
sulfur content fuels (S50, S350, S500, S800 and S1500). The investigations have been done on three unregulated
emission formaldeh de acetaldeh de MECHO as mentionedand SO2.
Formaldehyde emission was non-detectable. , , ,S800 and S1500 at two different speeds at 1900 rpm formaximum torque and 4000 rpm at maximum power withincreasin load in each case 0% 25% 50% 75% and 100%
loads).
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Effect of Engine Operating Condition and FuelEffect of Engine Operating Condition and Fuel
Com osition on Unre ulated EmissionCom osition on Unre ulated Emission
Fig 5: MECHO emission (n=1900 rpm) Fig 6: MECHO emission (n=4000 rpm)
Acetaldehyde emission decreases with increasing load and decreaseswith fuel sulfur content.
decreases with decreasing sulfur content in fuel.
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Effect of Engine Operating Condition and FuelEffect of Engine Operating Condition and Fuel
Com osition on Unre ulated EmissionCom osition on Unre ulated Emission
Fig 7: SO2 emission (n=1900 rpm) Fig 8: SO2 emission (n=4000 rpm)
SO2 emission increases with increasing sulfur content
As the fuel injection quantity increases, the emission of SO2 willncrease.
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Effect of Engine Operating Condition and FuelEffect of Engine Operating Condition and Fuel
Fig 9: SO2 reduction and fuel sulfur content (n=4000 rpm), [Tan et al9]
Calculated the average reduction extent of SO2 emission for five fuelswith different sulfur content keeping S1500 as base fuel.
Engine SO2 emission is directly related to the sulfur quality in the fuel.
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Effect of Engine Operating Condition and FuelEffect of Engine Operating Condition and Fuel
Composition on Unregulated EmissionComposition on Unregulated Emission
Fig 11: Effect of ethanol and engine load onformaldehyde emission
Fig 12: Effect of ethanol and engine load onacetaldehyde emission
Formaldehyde emission increases with the increase in engine loadand it decreases with the increase in alcohol content in ULSD. Thepossible reason is increased H/C ratio.
Decrease in acetaldehyde emission at high load because of high
combustion temperature.
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Effect of Engine Operating Condition and FuelEffect of Engine Operating Condition and Fuel
Table 3: Ethene, ethyne and 1,3-butadiene emissions at various engine loads.
1800(rev
min1)
0.20
MPa 0.38
MPa .55
MPa
C2H4 C2H2 C4H6 C2H4 C2H2 C4H6 C2H4 C2H2 C4H6
(ppm) (ppm) (ppm) (ppm) (ppm) (ppm) (ppm) (ppm) (ppm)ULSD 35.8 106 46.2 35 97.2 45.2 22.4 54.3 31.1
Blend1 44.7 109 49 30.1 82.8 44.4 19.2 45.7 24.3Blend2 23.7 49.6 29.5 22 43.5 28.1 14.4 26.4 21Blend3 33.6 62.5 41.1 28.1 47.5 35.8 16.8 28.1 21.8
Ethene and ethyne are the products of pyrolysis between diesel andethanol.
. . . . . . . .
C2H2 and C2H4 emission decreases with the increase of engine load.
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Effect of Engine Operating Condition and Fuel Composition onEffect of Engine Operating Condition and Fuel Composition on
Unre ulated EmissionUnre ulated Emission
Table 4: Benzene, toluene and xylene emissions atvarious engine loads.
mg KWh-1 0.20 MPa 0.38 MPa .55 MPa
C6H6 C7H8 C8H10 C6H6 C7H8 C8H10 C6H6 C7H8 C8H10
ULSD 79.2 17.1 69.7 57 8.3 33.2 28.1 3.3 18.7
Blend-1 95.9 8.7 58.3 54 4.3 28.9 23.6 2.6 17
Blend-2 97.2 9.1 38 53 4.3 18.2 20.8 2.5 10.6
Blend-3 112.6 9.4 55.3 48.9 4.1 24.5 26 1.9 12.5
Benzene oxidizes easily at high combustion temperature (high load).
Blend-4 153 13.8 66.8 63.4 5.8 25.3 30.3 3.2 13.4
Toluene and xylene also have the same trend as benzene.
At low engine load (low exhaust temperature) with high blend may.
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ConclusionsConclusions
It has been observed that addition of biodiesel with diesel reduced thecontent of aldehyde emission in the exhaust and the emission in hot startcondition NEDC test cycle is less than the cold start ADC test cycle.
Formaldehyde was by far most abundant carbonyl in the exhaust. Theconcentration of MECHO emission of the engine decrease with the fuelsulfur content.
The SO2 concentration increases with the engine load. SO2 emissiondecreases linearly with descending fuel sulfur content.
,emission reduces with increasing engine load. There is a sharp decrease inthe unburned ethanol emission with decreasing sulfur content.
,
load and decreases with the addition of ethanol in diesel with ultra lowsulfur content.
, . ,low combustion temperature leads higher BTX emission.
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Diesel Oxidation Catalysts (DOC)Diesel Oxidation Catalysts (DOC)
Oxidizes CO and HC to CO2 and H2O
desired
Oxidizes toxics such as aldehydes
xi izes 2 to 3 un esire
Oxidizes Soluble organic fraction (SOF,
Ceramic Catalyst
s a sor e on ar cu a es o re ucePM
PM reduction up to 50% depending on SOFcontent of PM; Typically 25% on new engines
DOC in a muffler
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Particulate Matter OxidationParticulate Matter Oxidation
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Catalyst
Carbon
SootCarbon
Soot
Note: Soluble Organic Fraction,
Vapor form.
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Diesel Catalytic Converter(Diesel Oxidation Catalyst)
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Oxidizes SOF fraction of PM Lower cell density and low back
constrains
Thermal & Chemical stabili ty ofcatalyst is a challenge May be useful under Indian
scenario, if fuel quality isimproved
Limitations
Lower particulate controlefficiency
Formation of sulfuric acid, sulfate
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Noble Metals vs NonNoble Metals vs Non--Noble MetalsNoble Metals
Pt, Pd, Rh cost !!Pt, Pd, Rh cost !!
,,
- Multicom onent s stems
Catalysis / Adsorption: Environmental Applications
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- Poor control on catalytic processes- Complex interface
-
- Chemical & thermal stability
- Cost, techno-economic feasibility
- Disposal , LCA (catalyst or adsorbent volume?)
- Phase transfer not feasible
Non-Noble Metal Based Catalysts
Very wide range of catalysts: metals; metal complexes; oxides;composites mixed oxides; perovskites; etc
Many industrial applications- From Fe based catalyst for Habersprocess to Ti-silicalite, Ceria to SnO2
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Mixed Oxides and Perovskites
Advantages:
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- Low cost: - Sometimes cost is not a ig issue- Disposable type catalysts ? VOCs Environmental issues ??
- Tailoring possibilities
- New designs (still coming up !!)-- Combinatorial approaches
- Thermal stabilit or combustion reactions etc
Limitations: - Surface area, microporosity (per unit SA activity !!)
- Low temperature activity
-
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on nuousy egenera ng rap
CRTCRT Particulate FilterParticulate Filter Operating PrincipleOperating Principle
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Use of NOx Within CCRT SystemUse of NOx Within CCRT System
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CRT Filter SystemCRT Filter System
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CContinuouslyontinuously RRegeneratingegenerating TTraprap Principle
Oxidation of NO to NO2 inside Pt catalyst
Conversion of stored soot in trap by NO2
Continuously Regenerating Trap (CRT)
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Utilize the strong oxidizing property of NO2Unit consists of P based catal st u stream of Filter to oxidize NOto NO2
NO2 oxidizes the soot(C) into CO2 in the trap
+ ---> +CO(g) + NO2(g) ---> CO2(g) + NO(g) (2)
2 NO(g) + O2(g) ---> 2 NO2(g) (3)
This system is very sensitive tosulphurcontent of fuel (S
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urner regenerat on system
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Electrical Regeneration
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A device that vastl reduces emission of
particulate matter (the main particle
com onent of black smoke from dieselengines of buses
Mitsubishi DPF System
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S stem
Mitsubishi put this system for practical use first time in Japan in busessucceeded in removing 80 % of PM even removes 100 % of black smoke
Overview of the Mitsubishi DPFOverview of the Mitsubishi DPF
ystemystem
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ystemystem The Mitsubishi DPF System traps particulate matter
in a porous ceramic i ter, an t is accumu ateparticulate matter is periodically burned. By
re ularl exchan in two filters to continuousl traand burn particulate matter, it can be continuouslycollected while the bus is running.
Overview of the Mitsubishi DPFOverview of the Mitsubishi DPF
ystemystem
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ystemystem
System Overview Two filter assembl
Exhaust gas control valve
Air flow sensor, temperature
& pressure sensors
Electric heater & convectorThe Mitsubishi DPF System.
Overview of the Mitsubishi DPFOverview of the Mitsubishi DPF
ystemystem
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ystemystem
Particulate matter collection
The fil ters use a heat-resistant, finely porous ceramic material. These pores,
Using 2 filters, exhaust gas is passed through one filter until the
accumulation level reaches a specified point, at which the exhaust gas flow
matter col lection by the other fil ter
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Approximately 80% of particulate matter is eliminated,
achieving output levels of only half those specified in theong- erm ex aus gas res r c on arge .
Moreover, black smoke, which accounts for most (65%)
of articulate matter, is 100% eliminated, makin exhaust
invisible to the eye.
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Effectiveness of particulate
matter reduction.
Effectiveness of black smoke
reduction.
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art a ow tersart a ow ters
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